Technical Abstract:
Animal manures are major sources of the organic phosphorus and are attracting a great deal of interest because of the inefficiency of animal digestive systems in absorbing or retaining phosphorus, in particular myo-inositol hexakis dihydrogenphosphate. Although there have been many studies on the composition and fate of inorganic P in manure and manure-amended soil, speciation of organic phosphorus compounds is yet poorly understood. The knowledge gap hampers the understanding of the environmental behavior and transformations of inositol phosphates in animal feed, manure, soil, water, and mixed environmental media thus the development of comprehensive strategies for mitigating agricultural phosphorus transfers to aquatic systems. In this chapter, we shall examine the factors that affect the processes of solubilization and dephosphorylation of dissolved and insoluble complexes of myo-inositol hexaphosphate to replenish the water-soluble phosphorus fraction and elaborate on a mild in situ ligand-based enzymatic method used to obtain insights about the biological stability of inositol phosphates in animal manure. Selected polydentate ligands and fungal phytases are found able to differentiate the various reserve pools that contribute to the solution-phase orthophosphate concentration of dairy manure and manure-amended soils. In such carbon-rich media and the ubiquitous presence of monoester phosphohydrolases, biological and biochemical mechanisms may more adequately reflect the availability of manure phosphorus pools to microorganisms and plants over time. Moreover, these mechanisms can reveal the underlying potential for the timed release and dephosphorylation of inositol phosphates in complex media to the environment.